Because Facebook isn't a "media" company, as soon as it's legally forced to become one it's forced to take on "editorial oversight" and then is subject to the laws that govern newspapers etc.
And, therein, lies the problem. The whole of cyberspace has been the "Wild, Wild, West" since the day of its inception and no one in a position to regulate it has ever bothered. Contrast that to both media companies and telecommunications, the former of which became regulated over a long period with additions as necessary, and the latter of which became regulated very early in its existence.
I am so sick to death of people who believe that laws, rules, and regulations spring up, unbidden, from some mythical "Department of Bureaucracy Creation," rather than coming into existence, usually slowly and with a lot of deliberation, in response to clear problems that they're trying to solve. We all know that the actual results can vary, but we also know that allowing the untenable to continue unabated is much, much worse.
The unwillingness to look at the world, and its technologies, and how they're being used and abused as they really are is the worst form of willful blindness and it's having devastating results. And a huge part of that is because (in the USA) decades have been spent actively cultivating a voter base that is actively antagonistic to facts, expert opinion, and the application of logic and reason to problem-solving. Critical thinking skills as part of most of the body politic has seemingly vanished. No one put it better, with a real world example of the time, than this:
The terrible state of public education has paid huge dividends in ignorance. Huge. We now have a country that can be told blatant lies — easily checkable, blatant lies — and I’m not talking about the covert workings of the CIA. When we have a terrorist attack, on September 11, 2001 with 19 men — 15 of them are Saudis — and five minutes later the whole country thinks they’re from Iraq — how can you have faith in the public? This is an easily checkable fact. The whole country is like the O.J. Simpson jurors.
~ Fran Lebowitz in
Ruminator Magazine interview with Susannah McNeely (Aug/Sept 2005)
Things have not gotten the slightest bit better, they've gotten much worse, since 2005.